1. Field of the Invention
The present invention relates to a vessel propulsion apparatus that propels a vessel.
2. Description of the Related Art
U.S. Pat. No. 8,147,285 discloses a vessel propulsion apparatus that includes an outboard motor. The outboard motor includes a drive shaft that is rotationally driven by an engine, a drive gear that is connected to the drive shaft, a front gear and a rear gear both of which engage the drive gear, and a dog clutch that selectively engages either one of the front and rear gears. The outboard motor further includes an intermediate shaft member that rotates together with the dog clutch, a propeller shaft that rotates together with a propeller, and a planetary gear mechanism that transmits the rotation of the intermediate shaft member to the propeller shaft.
As shown in FIG. 4 of U.S. Pat. No. 8,147,285, an oil passage of the outboard motor includes a through hole that passes through the intermediate shaft member in a radial direction and an oil passage portion that extends rearwardly from the through hole of the intermediate shaft member along a center line of the intermediate shaft member. The oil passage of the outboard motor further includes a main passage that extends rearwardly from a front end surface of the propeller shaft along a center line of the propeller shaft and a plurality of branch passages that diverge from the main passage inside the propeller shaft. The dog clutch is disposed around the through hole of the intermediate shaft member, and the planetary gear mechanism is disposed around the branch passages of the propeller shaft.
U.S. Pat. No. 8,147,285 discloses that oil is supplied to the planetary gear mechanism via the branch passages of the propeller shaft. Oil to be supplied to the branch passages is allowed to flow from the through hole, which opens at an outer peripheral surface of the intermediate shaft member, into the intermediate shaft member, and is guided to the branch passages by the main passage of the propeller shaft. The through hole of the intermediate shaft member that is equivalent to an oil inlet is disposed so as to open in a space between the front gear and the rear gear in a front-rear direction. However, in this outboard motor, a plurality of members, such as the drive gear and the dog clutch, are disposed around the through hole of the intermediate shaft member that is equivalent to an oil inlet, and thus the route of oil around the oil inlet is complex, and the flow of oil toward the oil inlet is obstructed by the plurality of members. Additionally, the space in front of the front gear and the space behind the front gear are partitioned by the front gear, and thus the flow of oil in both spaces is low.